This invention relates to an iron complex useful for iron fortification of processed foods. More particularly, this invention is directed to sodium-free, iron II EDTA complexes and their use in the manufacture of food additives for use in fortification mixtures and iron-fortified processed foods.
Nutritional iron deficiency affects a significant portion of the world""s population. It has been recognized as a cause or a contributing factor to anemia and other physiological conditions that adversely affect performance. For that reason the use of iron supplements for fortifying processed foods to help prevent and treat iron deficiency has become a common practice in most countries throughout the world. While there are many food acceptable iron fortificants that provide adequate quantities of bioavailable iron, such fortificants can adversely affect the organoleptic properties of the iron fortified processed foods. Food iron fortificants can be roughly divided into two groups: those which are have high bioavailability, high solubility, and low stability and those which have low bioavailability, low solubility, but good food stability. Chelated forms of iron like those of the present invention, on the other hand possess good bioavailability, good solubility, and good food stability. Most recently, sodium ferric ethylenediamenetetraacetic acid complex (hereinafter xe2x80x9cferric EDTAxe2x80x9d) has been studied primarily for fortification purposes due to its chemical stability and good bioavailability in the presence of interfering natural iron inhibitors such as phytic acid. It has been found to be suitable for fortifying foods that require prolonged storage or high temperatures during preparation. Ferric EDTA has been reported to be two to three times more bioavailable than iron presented as a ferrous sulfate complex in some diets especially those which have high levels of iron inhibiting substances. More recently ferric EDTA has been described for use in fortification of ready-to-eat cereals either by preparing the cereal product by incorporating ferric EDTA into the cereal mix prior to cooking or by spraying a ferric EDTA solution onto the cereal product.
However, the use of ferric EDTA as an iron fortificants does have the disadvantage that it is provided, by definition, as a sodium ferric EDTA complex which means it contains sodium. Thus its use adds undesirable sodium content to the ferric EDTA fortified food products. Moreover, while the iron III component of the ferric EDTA complex is protected somewhat in its EDTA complex form from absorption blocking complexation with dietary phytic acids, iron III is known to be susceptible to such adsorption blocking complexation in the digestive tract. Also, the EDTA complexes of this invention offer the added advantage of being able to deliver other crucially needed minerals including magnesium and calcium instead of sodium. The complexed iron species is divalent iron (iron II) which is the form required for absorption in humans. Also the intimate use of reducing agents along with the EDTA form is taught to maintain the iron II EDTA in its most available oxidation state. Accordingly, there is still need for development of food acceptable bioavailable iron containing complexes which do not suffer from the disadvantages still extant with use of ferric EDTA as an iron fortificant.
Thus, it is one object of this invention to provide sodium-free iron II ferrous iron EDTA complexes and food additive compositions containing said complexes that do not suffer from the disadvantages of the use of ferric EDTA. Such sodium-free iron II complexes can be isolated in crystalline, substantially pure form and used directly as an iron fortificants of processed foods or as a component of food additive fortification mixtures.
In one embodiment of the invention there is provided a food additive composition comprising a sodium-free iron II EDTA complex in combination with a food-acceptable antioxidant or reducing agent and a nutritional or non-nutritional food acceptable diluent or carrier. In still another embodiment of the present invention there is provided an iron-fortified processed food product comprising a plurality of nutritional food ingredients selected from the group consisting of protein, fat and carbohydrate and a sodium-free iron II EDTA complex. Optionally the processed food product comprises a food acceptable antioxidant or a reducing agent in an amount effective to prevent iron II oxidation during food processing or storage. In one embodiment the nutritional food ingredients of the food product are derived from cooked cereal grain. In another, at least a portion of nutritional food ingredients in the iron fortified processed food products of this invention are of dairy origin. The sodium-free iron II EDTA complex, alone or as a component of an iron fortification mixture composition, can be blended into a recipe of an unfortified processed food product to provide a product of high bioavailable iron content.
The present invention provides an iron fortificants for processed foods. Source of bioavailable iron for use in such compositions is a sodium-free iron II EDTA complex of the formula
(31 OCOCH)2NCH2CH2N(CH2COOxe2x88x92)2.Fe(II).2M
wherein M is selected from the group consisting of hydrogen, Ca++/2 and Mg++/2. The iron II complexes are prepared by combining solutions of stoichiometric amounts of ethylenediamenetetraacetic acid disodium salt, disodium calcium salt or disodium magnesium salt, respectively, with a source of iron II such as a water soluble ferrous salt (e.g., ferrous chloride) under nitrogen. The respective iron II complexes precipitate from reaction mixture and can be isolated by filtration, preferably under nitrogen. Attempted preparation of the corresponding iron II diammonium salt from ferrous chloride and ethylenediamenetetraacetic acid diammonium salt yielded the corresponding iron II EDTA diacid (M=H).
In one embodiment of this invention such sodium-free iron II complex, for example, the complex of Formula I wherein M is hydrogen, is isolated in a substantially pure, typically crystalline form, acceptable for food use. The complex is used to prepare a food additive iron-fortificant composition comprising the sodium-free iron II EDTA complex and a nutritional or non-nutritional food acceptable diluent or carrier therefor. In one embodiment the iron fortifying food additive composition further comprises a food acceptable antioxidant such as citric acid, tocopherols DHT, BHA, TBHQ or mixtures thereof, or food acceptable reducing agents such as sulfite or bisulfite salts in amounts effective to minimize iron II oxidation in the formulation. Nutritional diluent or carrier components of the iron fortificant composition can include proteins, fats, starches, sugars and the like. Examples of non-nutritional diluents or carriers include water insoluble bran or water soluble bran extracts such as beta-glucan, and food acceptable chemically modified cellulosics, including gums, glycosaminoglycans and the like. In one embodiment the diluent or carrier component of the food additive composition comprises a combination of nutritional and non-nutritional food acceptable components. The iron II complex typically comprises about 5% to about 80% by weight of the food additive composition, more typically about 10% to about 40% by weight of the composition and it is used in combination with effective amounts of a food acceptable reducing agent or anti-oxidant. A composition comprising an iron II complex of this invention can be used as an added ingredient in standard recipes for processed foods to provide high iron food products useful in treating or preventing dietary iron deficiency. Typically an amount of the sodium-free iron II complex is added to a processed food recipe to increase the iron content to a concentration of about 0.1 to about 40 mg/oz of product, or typically the amount of iron ranges from about 1 to about 25 mg/oz of processed food product. Thus another embodiment of the present invention is an iron fortified processed food product comprising a plurality of nutritional food ingredients selected from the group consisting of protein, fat, and carbohydrates and an iron II EDTA complex of Formula I. In one embodiment the food product recipe is further modified to include an effective amount of a food acceptable reducing agent or antioxidant in an amount effective to prevent or minimize iron II oxidation during processing and storage of the food product. In one embodiment the nutritional food ingredients of the processed food product comprise ingredients derived from cooked cereal grain. In another embodiment nutritional food ingredients of the processed food product comprise nutritional components of dairy origin. The iron complex or a food additive blend of such complex can be used as an added ingredient in the recipe of an unfortified processed food product. The amount of the complex or iron fortificant composition containing said complex added to said recipe is an amount sufficient to raise the iron content in the processed food product to a level of about 1 to about 40 mg./oz. In another embodiment a solution comprising an iron II complex of Formula I, optionally in combination with a food acceptable reducing agent or antioxidant, is sprayed onto the surface of a prepared processed food product, for example a ready-to-eat cereal product to raise the levels of bioavailable iron in said product.
The iron fortified foods available in accordance with this invention can be consumed as part of total dietary regimen to treat or prevent nutritional iron deficiency and associated clinical indications.